Heating induced aggregation in non-fullerene organic solar cells towards high performance

Molecular ordering within the photoactive layer plays a crucial role in determining the device performance of organic solar cells (OSCs). However, the simultaneous molecular ordering processes of polymer donors and non-fullerene acceptors (NFAs) during solution casting usually bring confinement effect, leading to insufficient structural order of photovoltaic components. Herein, the molecular packing of m-INPOIC NFA is effectively formed through a heating induced aggregation strategy, with the aggregation of PBDB-T, which has a strong temperature dependence, is retarded by casting on a preheated substrate to reduce its interference toward m-INPOIC. A sequent thermal annealing treatment is then applied to promote the ordering of PBDB-T and achieve balanced aggregation of both donors and acceptors, resulting in the achievement of a maximum efficiency of 13.9% of PBDB-T:m-INPOIC binary OSCs. This work disentangles the interactions of donor polymer and NFA during the solution casting process and develops a rational strategy to enhance the molecular packing of NFAs to boost device performance. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

The study successfully achieved a maximum efficiency of 13.9% for PBDB-T:m-INPOIC binary OSCs through a heating induced aggregation strategy and thermal annealing treatment, providing a practical method to enhance device performance.